Preparation of titanium monoxide by electrolysis



April 26, 1955 E. WAINER ETAL PRPARATION OF TITANIUM MONOXIDE BYELECTROLYSIS led Dec. 26

United States Patent O PREPARATION OF TITANIUM MONOXIDE BY ELECTROLYSISEugene Wainer, Cleveland Heights, and Merle E. Sibert,

Garfield Heights, Ohio, assignors, by mesne assignments, to HorizonsTitanium Corporation, Princeton, N. J., a corporation of New JerseyApplication December 26, 1950, Serial No. 202,805

7 Claims. (Cl. 204-61) This invention relates to the preparation ofsubstantially chemically pure titanium monoxide by electrolysis oftitanium dioxide in fused salt bath at elevated temperatures. Thepureness of the product concerns not only substantial freedom fromordinary chemical impurities, including higher oxides of titanium, butalso more importantly involves physical and structural purity from acrystallographic standpoint. The importance of such purity in thetitanium monoxide preparations enters not only in chemical usages forthe titanium monoxide, but also particularly where it is to be employedas a source for manufacture of titanium metal. It' suitable malleable,non-brittle and workable titanium metal is to be produced, it isessential that titanium monoxide employed as raw material must be freefrom impurities. In accordance with the present invention, titaniummonoxide may be had which meets the various requirements of purity fordifferent usages. Other objects and advantages of the invention willappear from the following description.

To the accomplishment of the foregoing and related ends, said inventionthen comprises the features hereinafter fully described and particularlypointed out in the claims, the following description setting forth indetail certain illustrative embodiments of the invention, these beingindicative, however, of but a few of the various ways in which theprinciple of the invention may be employed.

In its general aspects, the present invention involves the electrolyticproduction of titanium monoxide from titanium dioxide starting material.The titanium dioxide is charged into the anode compartment portion of aneleclytic cell separated into anode and cathode compartments by a porousbarrier extending from the bottom of the cell upwardly at least asubstantial distance toward the surface of a fused salt cell bath. Thecell bath comprises at least one halide of an alkaline earth metal or analkali metal, and advantageously a mixture of such halides. The fusedbath is maintained at a temperature value below that at which any halidecomponent of the bath decomposes, and under these conditionselectrolysis of the titanium dioxide-containing bath results inelectrolytic conversion of the titanium dioxide to titanium monoxide.The resulting titanium monoxide accumulates in and may be recovered fromthe cathode compartment of the cell. In commercial preference, thehalides used desirably are the chlorides of alkaline earth metals singlyor in mixture, or with addition of chlorides of sodium or potassium. ACaClz bath for instance operates at 780-925 C.; and CaClz 70 parts withNaCl 30 parts operates at around 750 C., and CaClz 60 parts with 20parts each of NaCl and KCl operates at 70D-750 C., while CaClz 60 partswith MgCl2 40 parts operates at 80G-850 C. The range of operation ingeneral is 70D-925 C.

Compartmented electrolytie cells in which the process of our inventionmay be advantageously carried out are shown in the drawings in which:

Fig. 1 is a sectional view of an inert atmosphere electrolytic cell inwhich the cell is divided into anode and cathode compartments by agraphite partition extending partway from the bottom of the cell to thelevel of eleclyte therein; and

Fig. 2 is a sectional view of an inert atmosphere cell divided intoanode and cathode compartments by a porous barrier extending from thebottom of the cell to above the level of electrolyte therein.

While many procedures have been described for the preparation oftitanium monoxide heretofore, these in rice general have failed toproduce satisfactorily pure titanium monoxide, and the products havecontained more or less of the undesirable higher oxides. For instance,it has been proposed to heat mixtures of powdered metal titanium anddioxide of titanium, or powdered titanium hydride and titanium dioxide,to elevated temperature in an inert atmosphere such as argon. Suchprocedures however are acedemic rather than commercial, for the reasonthat the raw material is disproportionately expensive. Also, it has beenproposed to reduce dioxide of titanium with metals of the alkali andalkaline earth series, hydrogen, etc., under varying conditions. ln eachcase however, there has been the drawback that satisfactorily puretitanium monoxide is not obtained, and there is the invariablecontamination by higher oxides. Such procedures also aredisproportionately expensive, and there is finally the necessity ofremoving by-products, and highly specialized secondary equipment isrequired.

In electrolytic decomposition of titanium dioxide in a fused halidebath, an impure product tends to be formed unless certain precautionsare taken. Higher oxides of titanium, and even traces of metal mayoccur. We have found, however, that if the procedure be carried out suchas to prevent access of materials from the anode zone to the cathodezone, chemically pure titanium monoxide is obtained etiiciently and athigh yields at the cathode zone. Under such conditions, the titaniummonoxide produced is free from higher oxides of titanium, and theproduct is well suited for use in electrolytic preparation of malleabletitanium metal.

The titanium dioxide raw material, such as pigment grade titaniumdioxide, may be mixed with a temporary binder, such as 8% water with0.5% starch, and then be pressed into pellets under pressures of theorder 2 to 10 tons per square inch, and the pellets then be tired in anoxidizing atmosphere to temperatures of the order of 2300" F. lf thesesintered pellets be crushed and sized to a grog particle size, e. g.1/16 to 1A inch there is a further gain in efficiency. And by chargingthe material in this form, for instance, in a graphite crucible anodezone or in the vicinity of a graphite anode which is inserted in a cell,the physical condition of the material favors its retention generally inthe anode zone instead of its being largely disseminated by turbulenceinto the cathode zone. The desired purity of titanium monoxide obtainedin this manner is satisfactory, but the efficiency can be raised stillhigher. lf a more effective separation of anode and cathode zone beenforced, the etliciency is increased, and thus if a barrier be providedbetween the anode and cathode zones, even though only a fraction of thetotal height of the electrolyte level, this affords substantiallycontinuous operation of the cell yielding a pure product withsatisfactory etiiciency.

An advantageous electrolytic cell arrangement by which our invention canbe carried out is Vshowin in Fig. 1. A graphite crucible 10 serving asthe container for the fused salt electrolyte is disposed within an inertatmosphere chamber 11 equipped with an inert gas, for example, argon,inlet pipe 12 and an outlet pipe 13. An electric resistance element 14provides the heat necessary to fuse and maintain at operatingtemperature the fused salt electrolyte 15 contained in the crucible 10.A graphite anode 16 extending through a packing gland 17 and a graphitecathode 18 extending through a packing gland 19 are immersed in thefused electrolyte 15. The crucible is divided into anode and cathodecompartments by a solid barrier of graphite 20 between the anode andcathode compartment. In such case, the anode compartment portion isdesirably roughly twice the volume of that of the cathode portion, andthe top of the graphite barrier 20 is somewhat below the level of theliquid bath. This form of device is particularly effective if the feedmaterial is supplied as relatively large particles of sintered titaniumdioxide 21. Another type of cell design which has operated well is shownin Fig. 2. In this construction we employ a graphite type crucible 10 asa container for the fused electrolyte 15 and as the cell anode, while acylindrical diaphragm 22 of sintered refractory ceramic such as Zirconor mullite having a porosity of about 20% is employed. Under theseconditions, the diaphragm 22 extends above the level of the bath and issutiiciently porous or permeable to permit ions to pass through, whileat the same time holding the solid particles of titanium dioxide 21back. The use of such a diaphragm necessitates a somewhat higher voltagebecause of the voltage drop across the diaphragm. Solid graphitediaphragms pierced with multitudinous fine holes also can serve. A thirdtype of diaphragm cell (not shown) which has been used effectively is inthe form of a porous refractory sleeve which completely surrounds agraphite anode. In this case, although a graphite crucible be used forthe container, the graphite anode does not come directly in contact withthe Crucible but is separated at the bottom by a fraction of an inch,while the porous sleeve rests on the bottom of the crucible and leavesan annular space to the graphite anode. The titanium dioxide feedmaterial may be in such case either in the form of finely divided powderor small sintered pellets placed in the annular space between thisporous sleeve and graphite anode. The importance of preventing bodilytransfer of titanium dioxide into the cathode zone has been shown by usby experiment. Titanium dioxide in powdered form is practicallyinsoluble in a molten calcium chloride bath, or in the various halidebaths suitable for the present purpose. As a result of the turbulentformation of gas at the anode, there is a tendency for finely powderedtitanium dioxide to become suspended throughout the entire volume of abath. Titanium monoxide is formed at the cathode, and in view of itshigh reactivity, tends to entrap and hold titanium dioxide encountered.As a result, higher oxides of titanium occur in a product formed undersuch conditions, and irrespective of the length of time in which theelectrolysis is carried out, no improvement in purity can result, sinceno means exists for transferring this cathode material back to the anodezone for continued purification. The use of sintered material, andparticularly plus a minor amount of compartmentalization, and still moreeffectively, further complete compartmentalization, diaphragming, etc.,prevents this kind of action, and the titanium dioxide and undesirableimpurities may be retained wholly in the anode zone, with resultantproduction of uncontaminated titanium monoxide in the cathode zone. Thereason for the effectiveness of sintered titanium dioxide is therelatively high density of such material as compared to that of themolten baths, and consequently the limitation on bodily transport intothe cathode zone.

The equipment used involves provision of inert atmospheres such as pureargon or helium in cell designs such that a positive pressure of theseinert gases may be available inside the electrolytic cell at all times.Crucibles used for the cells may be of graphite, although certainvitrified ceramics can also serve. The anodes are invariably of graphiteor carbon, and the cathodes may be graphite or a metal such as nickel ormolybdenum. The cells should be suitably formed for influx of the argonor other inert gas, addition of reagents, insertion of electrodes, etc.Argon or the like should be purified from oxygen, nitrogen, carbon andwater vapor impurities, by passage through suitable purification trains,and the gas may be recirculated through such trains after use forreasons of economy.

The fused bath material comprises alkaline earth halides or mixtures ofsuch alkaline earth halides with or without the addition of sodium andpotassium chlorides or combinations thereof. Thus, the anhydrouschlorides of calcium, magnesium, strontium, and the barium may be usedseparately, or combinations of these may be employed, or one or more ofthe alkaline earth halides in combination with sodium or potassiumchloride or a mixture of sodium potassium chloride. The preferred bathmaterial from the standpoint of economy, ease of operation and the like,is generally based on calcium chloride, mixtures of calcium chloride andmagnesium chloride, or calcium chloride plus one or more of sodium andpotassium chloride.

The temperature of operation is generally in the range of 900-925" C.When the bath is heavily complexed so that it contains a combination ofcalcium and magnesium chloride and of sodium and potassium chloride, thetemperature of operation may be reduced as low as 750-800 C. Themechanism of action in the operation is obscure, and we are notcommitted to any theory. The important fact is that it is necessary tocontrol the reaction temperature of the electrolysis carefully, since ifthe temperature is allowed to rise much above 925 C., the bath itself isattacked, being electrolyzed and depleted, and calcium may be given offat the cathode. When properly carried out, the bath level remainssubstantially constant.

In the final analysis, the sole final reaction which takes place is asimple reduction of titanium dioxide to the desired pure titaniummonoxide. The electrolysis is generally carried out with an E. M. F. offrom 5 to 7 volts. If a diaphragm or compartment is used, the voltagerequired is of the order of 10 to l2 volts, and the amount of theincrease is determined by the porosity and thickness of the diaphragmand the resulting potential drop across this diaphragm. All currentdensities from 1 up to at least 500 amperes per square decimeter at thecathode appear to be effective and in the small sized laboratory cells,current densities of the order of 300 to 400 amperes per squaredecimeter are used. It appears that the voltage and current requirementsare not critical within the limits given.

It has been indicated in the foregoing that some loss in efliciencydevelops if the bath temperature is allowed to rise too high and theupper limit at which this loss in efficiency starts to become evident isaround 1000-1050" C. Thus, for insurance purposes, the bath temperatureis maintained at about 925 C. or below. In preparing the bath materials,it is an absolute necessity that these reagents be completely anhydrousand standard methods are used for preparation of the anhydrous agents.

Titanium monoxide, the desired end product, is formed as a powder in thecathode compartment and the process may be made continuous bycirculating the cathode liquid into a third compartment from which theelectrolyte is continuously ladled out for subsequent separation steps,

After the electrolysis is completed, the cathode material is washed freeof halide by thorough water washing under a carbon dioxide atmosphere.The powder is then filtered and dried in a vacuum or at a temperaturenot exceeding 80 C. Under these conditions, it has been found thatsubstantially no oxidation takes place resulting in the harmful higheroxides of titanium. The product titanium monoxide is a golden brown hardpowder which when examined by X-ray procedures is shown to be chemicallypure titanium monoxide.

The nature of the reactions which take place in this electrolysis arenot clear, and we are not committed to any theory. The facts are thatcarbon monoxide is given off at the anode, no calcium metal is found inthe cathode material, and if the cell is operated within the temperaturelimits given in the foregoing, the efficiency is extremely high, bothelectrically and from a chemical yield standpoint.

If too high a level of temperature is used, calcium droplets appear inthe vicinity of the cathode and separate from the cathode, the course ofthe reaction being changed such that the bath itself is beingelectrolyzed to the formation of calcium, and correspondingly theefficiency both electrically and chemically falls, and the bath levelalso drops.

Illustrative of the procedure are the following examples:

Example 1.-A heated electrolytic cell is provided in which the anode isa graphite Crucible which contains the melt. The cathode is a sheet ofmolybdenum 0.5 square decimeter in area. The cell is compartmentalizedby the insertion of a solid graphite barrier in the central portions ofthe cell such that the anode compartment is roughly twice the size ofthe cathode compartment. This barrier extends to within about l to 1/2from the top of the electrolyte level. The electrolyte is fused CaClz.The cell is operated in the presence of a positive pressure of purifiedargon. The pure titanium dioxide feed is provided as a powder in theanode compartment. Electrolysis is carried out at 900 C. with a voltageof about 8 volts and a current of 400 amperes per square decimetei atthe cathode equivalent to 200 amperes total input. Typical yields ofmaterial are of the order of while the current efficiency is of theorder of 60% so that the cell is run for twice the theoretical time.This is expected since all of the anode area is not used in the process.On cooling, the bath is white with no trace of blue tinge. The bath isleached in water under carbon dioxide atmosphere and the product isrecovered by filtering and washing. It is then subsequently dried in avacuum or a temperature in an ordinary drier not exceeding 80 C. Typicalfigures are the following: 500 grams of calcium chloride, 50 grams oftitanium dioxide yielding 40 grains of titanium monoxide in 20 minutesat a current of 200 amperes.

Example 2.--A modification of the cell structure used in Example 1yields somewhat higher current efficiency. The same type ofcompartmentalized cell is used, but in this case, the graphite crucibleis electrically inert. A massive graphite anode almost filling the anodecompartment is inserted in the cell so that it is close to the walls ofthe graphite crucible, but is not touching. The titanium dioxide powderis placed in the annular space between the graphite anode and thegraphite crucible. Under these conditions, the same general chemicalyields are developed as in Example 1, but the current eiiiciency isaround 90% in that 40 grams of TiO are obtained in 13.5 minutes. Again,this is expected since a more effective use of the anode compartment isobtained.

Example 3.-The same general construction as described in Example l isused except that the comparutmentaliZing graphite barrier is omitted.The anode in this case is a graphite rod which extends almost to thebottom of the crucible. Surrounding the graphite rod is a porous sleeveof a Zircon porcelain consisting of substantially pure high tiredzirconium silicate tired to a porosity of the order of Titanium dioxidefeed material is placed in the annular space between the graphite anodeand the Zircon sleeve. Material yields are quantitative while currentyields are of the order of 85 to 90%.

Example 4 In this case, the crucible is a dense iired pure Zircon whichis non-porous. The diaphragm of porous Zircon is placed in the middleportion of the cell and this diaphragm extends above the top of theliquid. The anode isa massive graphite rod and the cathode iSmolybdenum. The anode almost fills the anode compartment. Titaniumdioxide is placed in this area. Chemical yield is quantitative andcurrent yields are 90 to 95%, 40 grams of TiO being obtained in about l2minutes at 200 amperes.

Example 5 .-A cell without compartments is provided made of graphite.The same cell structure as in Example 3 is used. The feed material iscrushed titanium oxide sinter having a particle size in the range of1/16 to Mt of an inch. This is heaped in a pile around the anode in theanode sections of the cell.

Example 6.-A graphite crucible is provided as the container. Again thecathode is a molybdenum sheet. A porous Zircon crucible is used as theanode compartment in which a massive graphite anode is placed. Titaniumoxide feed material is in the form of sintered tiitanium oxide grogwhich is placed inside this porous Zircon crucible. This method providespositive separation of titanium dioxide from the titanium monoxide formsimply by lifting the porous crucible out of the bath at any desiredtime.

Example 7.-A graphite crucible is container and anode. The cathode iscompartmentalized by placement in a purified Zircon crucible submergedbelow the surface of the electrolyte. The crucible rests on the floor ofthe container crucible. Sintered TiOz grog is placed in the electrolytein the anode area outside the cathode compartment. The TiO formed isretained in the removable cathode container.

There are many obvious modifications of the diaphragm and compartmenttype cells such as have been described in the foregoing specification assuitable for use in the process, and no attempt has been made to exhaustall the possibilities of construction. The important point to consider,however, is that it is vitally necessary to separate the anode andcathode products of reaction completely so as to prevent any possibilityof the higher oxides of titanium being present in the end product. Themeans which have been described in this specification are suflicientlyeffective for the purposes for which titanium monoxide are eventually tobe put.

Other modes of applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of the following claims or the equivalent of suchbe employed.

We therefore particularly point out and distinctly claim as ourinvention:

1. The method of producing substantially pure titanium monoxide whichcomprises providing an electrolytic cell separated into anode andcathode compartments by a porous barrier, forming a fused salt baththerein consisting essentially of at least one halide salt of the groupconsisting of alkaline earth metal halides and mixtures of alkalineearth metal halides and alkaline metal halides, charging solid titaniumdioxide into the anode compartment only of the cell, maintaining thefused bath at a temperature within the range between about 700 C. and925 C. and under a noble gas atmosphere, passing an electrolyzingcurrent through the fused bath between an anode and a cathode in contactwith said bath at a cell voltage such as to establish a cathode currentdensity within the range of 1 to 500 amperes per square decimeter andrecovering the resultant cathodically deposited titanium monoxide fromthe cell.

2. The method of producing substantially pure titanium monoxide whichcomprises providing an electrolytic cell separated into anode andcathode compartments by a porous barrier, forming a fused salt baththerein consisting essentially of at least one halide salt of the groupconsisting of calcium chloride, mixtures of calcium chloride and atleast one other alkaline earth metal halide and mixtures of calciumchloride and at least one alkali metal halide, charging solid titaniumdioxide into the anode compartment only of the cell, maintaining thefused bath at a temperature within the range between about 700 C. and925 C. and under a noble gas atmosphere, passing an electrolyzingcurrent through the fused bath between an anode and a cathode in contactwith said bath at a cell voltage such as to establish a cathode currentdensity within the range of l to 500 amperes per square decimeter andrecovering the resltllltant11 cathodically deposited titanium monoxidefrom t e ce 3. The method of producing substantially pure titaniummonoxide which comprises providing an electrolytic cell separated intoanode and cathode compartments by a porous barrier, forming a fused saltbath therein consisting essentially of at least one halide salt of thegroup consisting of alkaline earth metal halides and mixtures ofalkaline earth metal halides and alkali metal halides, charging solidtitanium dioxide into the anode compartment only of the cell,maintaining the fused bath at a temperature within the range betweenabout 700 C. and 925 C. and under an argon atmosphere, passing anelectrolyzing current through the fused bath between an anode and acathode in contact with said bath at a cell voltage such as to establisha cathode current density within the range of l to 500 amperes persquare decimeter and recovering the resultant cathodically depositedtitanium monoxide from the cell.

4. The method of producing substantially pure titanium monoxide whichcomprises providing an electrolytic cell separated into anode andcathode compartments by a porous barrier, forming a fused salt baththerein consisting essentially of at least one halide salt of the groupconsisting of alkaline earth metal halides and mixtures of alkalineearth metal halides, charging solid titanium dioxide into the anodecompartment only of the cell, maintaining the fused bath at atemperature within the range between about 700 C. and 925 C. and under anoble gas atmosphere, passing an electrolyzing current through the fusedbath between a carbonaceous anode and a cathode in contact with saidbath at a cell voltage such as to establish a cathode current densitywithin the range of 1 to 500 amperes per square decimeter and recoveringthe resultant cathodically deposited titanium monoxide from the cell.

5. The method of producing substantially pure titanium monoxide whichcomprises providing an electrolytic cell separated into anode andcathode compartments by a porous barrier, forming a fused salt baththerein consisting essentially of at least one halide salt of the groupconsisting of alkaline earth metal halides and mixtures of alkalineearth metal halides and alkali metal halides, charging sintered titaniumdioxide into the anode compartment only of the cell, maintaining thefused bath at a temperature within the range between about 700 C. and925 C. and under a noble gas atmosphere, passing an electrolyZingcurrent through the fused bath between an anode and a cathode in contactwith said bath at a cell voltage such as to establish a cathode currentdensity within the range of 1 to 500 amperes per square decimeter andrecovering the resultant cathodically deposited titanium monoxide fromthe cell.

6. The method of producing substantially pure titanium monoxide whichcomprised forming a fused salt bath consisting essentially of at leastone halide salt of the group consisting of alkaline earth metal halidesand mixtures of alkaline earth metal halides and alkali metal halides inan electrolytic cell containing an anode and a cathode maintaining thefused bath at a temperature within the range between about 700 C. and925 C. and under a noble gas atmosphere, charging solid sinteredtitanium dioxide in the vicinity of the cell anode and remote from thecell cathode, passing an electrolyzing current through the fused bathbetween an anode and a cathode in contact with said bath at a cellvoltage such as to establish a cathode current density within the rangeof l to 500 amperes per square decimenter and recovering the resultantcathodically deposited titanium monoxide from the cell, substantiallyfree from any higher oxides of titanium by withdrawing material from thevicinity of the cathode uncontaminated by any of the sintered titaniumdioxide charged in the vi cinity of the anode and extracting thetitanium monoxide from the withdrawn material.

7. The method of producing substantially pure titanium monoxide whichcomprises providing an electrolytic cell separated into anode andcathode compartments by a porous barrier, forming a fused salt baththerein consisting essentially of at least one halide salt of the groupconsisting of calcium chloride, mixtures of calcium chloride and atleast one other alkaline earth metal halide and mixtures of calciumchloride and at least one alkali metal halide, charging solid titaniumdioxide into the anode compartment only of the cell, maintainlReferences Cited in the tile of this patent UNITED STATES PATENTS VonKugelgen Oct. 4, 1904 OTHER REFERENCES Journal of Applied Chemistry (U.S. S. R.), vol. 13 (1940), pages 5l thru 55, article by Sklarenko etal., original in Russian.

"Chemical Abstracts, vol. 34 (1940), page 7756, abstract of article bySklarenko et al.

Titanium by Barksdale, published in 1949 by the Ronald Press Company, ofNew York, pages 41 and 43.

6. THE METHOD OF PRODUCING SUBSTANTIALLY PURE TITANIUM MONOXIDE WHICHCOMPRISED FORMING A FUSED SALT BATH CONSISTING ESSENTIALLY OF AT LEASTONE HALIDE SALT OF THE GROUP CONSISTING OF ALKALINE EARTH METAL HALIDESAND MIXTURES OF ALKALINE EARTH METAL HALIDES AND ALKALI METAL HALIDES INAN ELECTROLYTIC CELL CONTAINING AN ANODE AND A CATHODE MAINTAINING THEFUSED BATH AT A TEMPERATURE WITHIN THE RANGE BETWEEN ABOUT 700* C. AND925* C. AND UNDER A NOBLE GAS ATMOSPHERE, CARGING SOLID SINTEREDTITANIUM DIOXIDE IN THE VINCINITY OF THE CELL ANODE AND REMOTE FROM THECELL CATHODE, PASSING AN ELECTROLYZING CURRENT THROUGH THE FUED BATHBETWEEN AN ANODE AND A CATHODE IN CONTACT WITH SAID BATH AT A CELLVOLTAGE SUCH AS TO ESTABLISH A CATHODE CURRENT DENSITY WITHIN THE RANGEOF 1 TO 500 AMPERES PER SQUARE DECIMENTER AND RECOVERING THE RESULTANTCATHODICALLY DEPOSITED TITANIUM MONOXIDES FROM THE CELL, SUBSTANTIALLYFREE FROM ANY HIGHER OXIDES OF TITANIUM BY WITHDRAWING MATERIAL FROM THEVINCINITY OF THE CATHODE UNCONTAMINATED BY ANY OF THE SINTERED TITANIUMDIOXIDE CHARGED IN THE VICINITY OF THE ANODE AND EXTRACTING THE TITANIUMMONOXIDE FROM THE WITHDRAWN MATERIAL.